1. The Field of the Invention
The present invention relates to armor plates and articles of manufacture incorporating the armor plates.
2. The Relevant Technology
Armor is a material or system of materials designed to protect from ballistic threats. Transparent armor, in addition to providing protection from the ballistic threat is also designed to be optically transparent, which allows a person to see through the armor and/or to allow light to illuminate the area behind the armor.
In the general field of ballistic armors, existing armor systems are typically comprised of many layers of projectile resistant material separated by polymer interlayers, which bond the projectile resistant materials. In a typical armor laminate the strike surface is a hard layer of projectile resistant material that is designed to break up or deform projectiles upon impact. The interlayer materials are used to mitigate the stresses from thermal expansion mismatches as well as to stop crack propagation into the polymers.
For most armor plates, efforts are usually made to make the armor plate light weight. This is particularly true of transparent armor plates, which are often used for protective visors and goggles. Currently existing military specification for protective visors and goggles requires that the lens should be able to stop .22-caliber 17 grain FSP projectile at 550-feet per second (fps). For comparison, most handguns give more than 1000 fps bullet velocity and rifles up to 3000 fps. To stop bullets from handguns one needs an inch thick polycarbonate plate and around two inches thickness for a rifle bullet.
Accordingly, what is needed in the art are armor plates that have improved resistance to a projectile for a given weight and/or thickness.